Question: Express your answer as a mixed number simplified to lowest terms. $12\dfrac{1}{20}-10\dfrac{4}{10} = {?}$
Solution: Simplify each fraction. $= {12\dfrac{1}{20}} - {10\dfrac{2}{5}}$ Find a common denominator for the fractions: $= {12\dfrac{1}{20}}-{10\dfrac{8}{20}}$ Convert ${12\dfrac{1}{20}}$ to ${11 + \dfrac{20}{20} + \dfrac{1}{20}}$ So the problem becomes: ${11\dfrac{21}{20}}-{10\dfrac{8}{20}}$ Separate the whole numbers from the fractional parts: $= {11} + {\dfrac{21}{20}} - {10} - {\dfrac{8}{20}}$ Bring the whole numbers together and the fractions together: $= {11} - {10} + {\dfrac{21}{20}} - {\dfrac{8}{20}}$ Subtract the whole numbers: $=1 + {\dfrac{21}{20}} - {\dfrac{8}{20}}$ Subtract the fractions: $= 1+\dfrac{13}{20}$ Combine the whole and fractional parts into a mixed number: $= 1\dfrac{13}{20}$